1. Technical Field
The present invention relates to a belted absorbent article in the form of a diaper, an adult incontinence garment, and the like, comprising an absorbent structure and a pair of opposed belt halves attached to the absorbent structure at an end region thereof.
2. Discussion of Related Art
Conventional diapers for young children generally comprise an absorbent structure made up of an absorbent core sandwiched between a liquid pervious topsheet and a liquid-impervious backsheet. The absorbent structure has a front panel generally covering the child""s abdomen when worn and a rear panel generally covering the child""s buttocks. The front and rear panels terminate in front and rear end regions respectively. In order to secure the diaper about the child, the front and rear end regions are provided with cooperating fastening means, for example in the form of a hook-and-loop fastening system or, alternatively, an adhesive tape tab system on the rear end region cooperating with a landing zone on the front end region. To fit the diaper to the child, the child is normally laid down on his/her back, the diaper is inserted under the child such that the rear panel covers the child""s buttocks, the front panel is drawn between the child""s legs to cover the abdomen and the fastening system is employed to join the longitudinal sides of the respective front and rear end regions together.
Since it is almost exclusively a guardian who changes a child""s diaper, the above-described method of securing a diaper to a child is generally fully satisfactory. However, particularly for incontinent adults who are capable of changing their own diapers, such a method of securing an absorbent article about the body is inconvenient, primarily because the act of securing the absorbent article about the adult body is conducted when standing. Thus, it is awkward for the wearer to simultaneously hold the absorbent article to the body in its correct orientation whilst fastening the front and rear end regions to each other.
To at least partially alleviate the above-mentioned inconvenience, belted absorbent articles have been proposed. For example, a belted absorbent article is disclosed in FR-A-2 586 558 in which a one-piece belt is attached to the backsheet of an absorbent structure. The article is secured about the wearer by bringing the article to the rear of the wearer to thereby cover the buttocks, fastening the belt about the waist of the wearer and then drawing the front end region of the absorbent structure between the legs of the wearer and attaching the front end region to fastening means on the belt.
EP-B-0 729 329 discloses a belted absorbent article in which, rather than using a single belt attached to the absorbent structure, two belt halves are employed, with each belt half extending from a respective longitudinal edge of the absorbent structure. An advantage of this construction over that disclosed in FR-A-2 586 558 is that less belt material is needed. However, because two belt halves are employed, the joint between each belt half and the absorbent structure must be capable of withstanding the tension forces to which the belt halves are typically subjected during use.
Particularly in terms of adult incontinence diapers, the size of wearers varies greatly. In order to rationalize production and storage as much as possible, it is preferable to have as few product size variations as possible. This implies, on the other hand, that each product size must be capable of fitting wearers of widely diverging shape and size. As a consequence, the forces to which the belt halves are subjected during use will be, at least to a certain extent, dependent on the size of the wearer. To keep manufacturing costs low, it is of course advantageous to use as little material as possible. Nevertheless, a product must be sufficiently strong to fulfil its intended purpose.
As is apparent from FIG. 1, when a belted absorbent article 10 is secured to a wearer, an angle xcex1 is created between, in effect, the longitudinal axis L of the belt half and the transverse axis T of the absorbent structure (it being assumed in the illustrated embodiment that the longitudinal edge of the belt half is parallel to the longitudinal axis of the belt half). Depending on the size of the wearer in relation to the size of the article, the value of xcex1 will vary. The greater the size of wearer, the greater the value of xcex1 will be. As the angle xcex1 increases, an increasing shear force is applied to the joint between the belt half and the absorbent structure.
The present applicant has discovered that, in order for a belted absorbent article to function satisfactorily, while still keeping manufacturing costs as low as reasonably possible, the joint between each belt half and the absorbent structure should preferably meet certain minimum requirements depending on the angle xcex1.
It is therefore an object of the present invention to provide a belted absorbent article which functions satisfactorily while still keeping manufacturing costs as low as reasonably possible.
This object is achieved by means of the belted absorbent article comprising an absorbent structure extending about a first longitudinal axis, the absorbent structure including a topsheet, a backsheet and an absorbent batt disposed between the topsheet and the backsheet, the absorbent structure having a transverse axis dividing the absorbent structure into a front panel terminating in a front end region and a rear panel terminating in a rear end region, the absorbent structure being delimited by opposed longitudinal edges and opposed transverse edges, and a pair of opposed belt halves attached to the absorbent structure at the rear end region of the rear panel by a respective joint, each belt half extending about a second longitudinal axis such that each belt half extends outwardly from a respective longitudinal edge of the absorbent structure. The joint between each belt half and the absorbent structure is designed such that when each belt half is subjected to a tension force of 35 N acting along the second longitudinal axis and the second longitudinal axis creates an angle xcex1 to said transverse axis of said absorbent structure, the following minimum average release times (t) of each said belt half from said absorbent structure are attained:
when xcex1=10xc2x0, t greater than  greater than 720 seconds;
when xcex1=20xc2x0, t greater than  greater than 330 seconds;
when xcex1=25xc2x0, t greater than  greater than 240 seconds;
when xcex1=30xc2x0, t greater than  greater than 180 seconds; and
when xcex1=40xc2x0, t greater than  greater than 75 seconds.
In a preferred embodiment of the invention, the following minimum average release times (t) of each belt half from the absorbent structure are attained:
when xcex1=10xc2x0, t greater than  greater than 740 seconds;
when xcex1=20xc2x0, t greater than  greater than 340 seconds;
when xcex1=25xc2x0, t greater than  greater than 245 seconds;
when xcex1=30xc2x0, t greater than  greater than 190 seconds; and
when xcex1=40xc2x0, t greater than  greater than 80 seconds.
In a more preferred embodiment of the invention, the following minimum average release times (t) of each belt half from the absorbent structure are attained:
when xcex1=10xc2x0, t greater than  greater than 760 seconds;
when xcex1=20xc2x0, t greater than  greater than 350 seconds;
when xcex1=25xc2x0, t greater than  greater than 250 seconds;
when xcex1=30xc2x0, t greater than  greater than 200 seconds; and
when xcex1=40xc2x0, t greater than  greater than 85 seconds.
In a further embodiment of the invention, the following minimum average release times (t) of each belt half from the absorbent structure are attained:
when xcex1=10xc2x0, t greater than  greater than 780 seconds;
when xcex1=20xc2x0, t greater than  greater than 360 seconds;
when xcex1=25xc2x0, t greater than  greater than 255 seconds;
when xcex1=30xc2x0, t greater than  greater than 210 seconds; and
when xcex1=40xc2x0, t greater than  greater than 90 seconds.
In accordance with a most preferred embodiment of the invention, the following minimum average release times (t) of each belt half from the absorbent structure are attained:
when xcex1=10xc2x0, t greater than  greater than 800 seconds;
when xcex1=20xc2x0, t greater than  greater than 370 seconds;
when xcex1=25xc2x0, t greater than  greater than 260 seconds;
when xcex1=30xc2x0, t greater than  greater than 220 seconds; and
when xcex1=40xc2x0, t greater than  greater than 100 seconds.
Thus, in accordance with the invention, by ensuring that the joint between each belt half and the absorbent structure can withstand a force of 35 N at predetermined values of the angle xcex1 for a minimum average release time per chosen angle, it has been found in practice that failure of the belted absorbent article due to loosening of the belt halves does not occur, at least not during normal use.